Cabletron Systems 04-0053-01 manual Port Congestion, Min = 256, Max =

Troubleshooting Troubleshooting Congestion

Table 9-1 Settings for Class of Service Queues (Continued)

Service Class	Recommended Settings
rt-VBR	Bandwidth* utilization less than 20%: Min = 16, Max = 1024
rt-VBR	Bandwidth* utilization greater than 20%: Min = 128, Max = 4096
Nrt-VBR	Min = 256, Max = 4096
UBR	Min = 256, Max = 8192
ABR	Min = 256, Max = 8192

*Use the show portconfig command to view bandwidth utilization

3.Has the congestion subsided?

•If yes, you are done.

•If no, continue.

4.Have you changed the EPD threshold (set switchtrafficcongestion command)?

•If yes, replace it to the default setting. If congestion subsides, you are done.

•If no, continue.

5.Enter the show cacinfo and show portconfig commands for each port. Is the allocated bandwidth small and is the traffic mostly UBR?

•If no, go back to step 4 and check next port.

•If yes, continue.

6.Enter the show porttrafficcongestion command. Is the UBR queue MaxValue large?

•If no, go back to step 4.

•If yes, continue.

7.Reduce the UBR queue MaxValue by a small amount, then wait a few minutes.

8.Enter the show portstats command, and take the default of all. Is the number of cells dropped increasing for this port, and quickly decreasing for all other ports?

•If yes, proceed to the “Port Congestion” section.

•If no, continue.

9.Is the number of cells being dropped by all other ports decreasing somewhat?

•If no, go back to step 6.

•If yes, continue.

10.Enter the set caceqbwallocscheme command and set call admission control for this port to a more conservative policy (moderate or conservative).

11.Go back to step 4 until all ports have been checked.

9.4.3Port Congestion

1.Enter the show portstats command a few times, noting the value for cells dropped and unknown VCs dropped. Is the number of cells dropped equal to the number of VCs dropped?

SmartSwitch ATM User Guide 9-5